I currently have a 164 white solf 1.1 that I love to throw. Reading some threads here I get the impresion that the 1.3 run is different. Does it throw completely different or can I break in a 1.3 to fly like my 1.1?

They will fly different out of the box but I have not thrown a 1.3 long enough to break it in. The slanted inner rim (+ mold) on the 1.3 didn't mesh well with my grip. A 1.2 OLF will fly closer to the 1.1 SOLF in my opinion. A 164 1.1 SOLF is my main driver and has been for a while.

Not all 1.3's are plus molds. I have two or three that aren't. The only ones I've seen that have slanted rims are the absurdly domey max-weight ones.

Also, I've never thrown a 1.1, but from what I understand, they are a little less overstable than the 1.2's. My non-plus 1.3's are definitely less overstable than my 1.2's, so maybe it's close to a 1.1. I can't be completely sure, though.

I threw a slightly seasoned 163 1.1 SOLF and a new 163 1.3 SOLF. The new 1.3 was of a softer plastic. The 1.3 was just a tick overstable but it was brand new. So, I say they are as close to the same disc as possible. Oh, both were white.

In this case, maybe, the "plus" mold shape of some of the 1.3's is unintentional. Sometimes the slanted rim comes from the way the plastic cools and shrinks, IIRC from some things I've read on this board. Again, I've only noticed the "plus" feel on domey max-weights, so maybe the two are related.